1. Field of the Invention
This invention relates generally to the field of cargo transport. More specifically, this invention is concerned with cargo containers that may be converted to carry a wide variety of material having different characteristics and densities. The present invention finds particularly useful application in the field of containerized cargo using so-called intermodal containers. It should be clear that the advantages of the invention are equally manifest in various types and sizes of containers.
2. Background of the Invention
Two of the major problems faced by the cargo industry were the desire to quickly transfer cargo from one mode of transport to another and the so-called "backhaul" or "deadhead" problem created when a carrier was forced to travel some distance empty, since he was not equipped to carry the type cargo available.
In response to the growing demand for a simple method of transferring cargo from one mode of surface transport to another, intermodal containers have been developed. These containers are designed to meet International Standards Organization (ISO) specifications, and are generally 8 feet high by 8 feet wide by 10 to 40 feet long, in 10 foot increments. Generally use of this type of container has been with various means of surface transport, however, it has seen limited use in air transport. Recently lightweight containers of this type, specifically for air shipment, have become available.
Backhaul difficulties arise when a carrier transports, for example, solid cargo in one direction and is then forced to make the return trip empty since only fluent materials are available for shipment. Some efforts have been directed toward converting these carriers from one type of cargo to another, however such systems require not only a substantial amount of idle time for the carrier during conversion, but also a large amount of freight depot storage at each end of the route for the necessary hardware. Frequently, an excess of one type of hardware is stored at one end of the route, while the need for the hardware is at the other.
It has been suggested that these difficulties may be overcome by providing self-contained, convertible cargo containers. Typical prior efforts in this regard utilize, for example, a collapsable liner directly supported by the walls of the outer container and held in position by a bulky linkage assembly. Since such containers are generally intended for use by surface transport means, little effort appears to be directed toward minimizing weight and bulk.
A related problem in the design of a convertible container is the different densities of solid and fluent cargo. Since fluent material, such as a liquid, is far more dense than solid cargo, a conversion design must compensate therefor by providing a smaller fluent container supported to evenly distribute the load. This factor is extremely critical in air transport where pressure of the liquid is accentuated by high acceleration forces during flight maneuvers.
One object of the present invention is to provide an intermodal container that may be quickly and efficiently converted from one type of cargo storage to another using elements and hardware that are always stowed within the container.
Another object of the invention is to provide a convertible container system wherein an inner, fluent material container may be removed and compactly stored so as to be efficiently transported by the carrier when not in use.
Yet another object of the present invention is to provide a convertible container system whereby all of the hardware necessary for converting the container from solid to fluent storage will either move out of the way within the container or be mounted and dimensioned so as to be removable from several containers and nestable within a single container.
It is another object of the invention to provide a convertible, intermodal container capable of utilizing the maximum allowable cargo density regardless of the type of cargo carried.
Another object of the invention is to provide a container capable of holding solid cargo on one end and fluent cargo on the other end.
A related object of the invention is to provide a convertible, intermodal container system wherein all elements and hardware necessary for conversion are carried with the transport, thus eliminating the necessity of destination storage.